When we're sizing a chiller, we go through a lot of different questions.
Pool size, desired temp, number of swimmers per day and peak periods - pretty typical questions.
The reason we ask these is because we need to figure out how much heat is going into the pool.
Once we know that, we can size the chiller.
If the chiller is too small, it can't remove as much heat as is being added, and the water temp will creep up.
If it's too big, it'll short cycle (cycle on and off every 5-10 seconds) and burn out the equipment prematurely.
But one heat load I didn't know would be so important is sunlight.
We do a lot of testing at Bergs.
Always testing new chillers, new designs and configurations.
Summer is our peak testing season.
If we can make it chill easily in summer when everyone else's chiller is failing, we know that's where we need to be.
A few summers ago we were testing during a 40+ degree week, putting the chillers on progressively larger bodies of water.
We wanted to see how different the heat load would be in direct sunlight vs shade.
The difference was much bigger than we thought.
On smaller pools, it was adding 4-5kw of heat, the equivalent of 6-10 swimmers.
On bigger pools, it was adding 10kw or more, that's around 20 swimmers constantly in and out.
The reason it was more on bigger pools is because there's a greater surface area of water being hit by the sun.
For this reason, we test our chillers on 5000 litre black rainwater tanks.
We connect multiple tanks to one chiller on the hottest summer days, and then we connect heaters to the tanks as well so we can truly test our chillers under the harshest pressures.
That way we know once they go out, we have no worries about performance.
This is a major reason we've only had one breakdown in the field (which was actually due to it not being service for a few years and the coils being caked in debris).
So when sizing up a chiller, always check if it is in direct sunlight.
It could be the difference between an ice bath and a not so icy bath.